One or more embodiments of the present specification relate to power generation systems and more particularly to power conversion unit employed in the power generation systems.
Typically, a power generation system includes a power conversion unit such as a back-to-back converter. The back-to-back converter includes a rotor-side converter and a line-side converter coupled to the rotor-side converter via a direct current (DC) link. A primary function of the back-to-back converter is to regulate active power and reactive power fed into a grid. The power generation system further employs bulky three-winding transformers to provide power to the grid from the back-to-back converter.
Usually, a combination of converters is used as a line-side converter to enhance a value of an output generated by the line-side converter. Further, the rotor-side and line-side converters of the power generation systems include multiple switches. Use of the multiple switches in the power conversion unit results in increased cost and electrical losses. Further, use of the multiple switches is associated with increased control complexity associated with firing of these multiple switches.
In addition, failure of a converter of the combination of converters in the line-side converter or failure of a switch of the multiple switches employed in the line-side converter may adversely affect a value of a line-side output. Further, as will be appreciated, in instances of such failures, reliability of the power conversion unit employing such line-side converter is compromised.
A modular arrangement of the power conversion unit is desirable to improve reliability of the power conversion unit. In recent times, various modular arrangements of power conversion units have been proposed. However, the existing modular arrangements of the power conversion units typically employ a plurality of DC-DC converter stages. Furthermore, each line-side converter of the modular arrangement of the power conversion unit typically provides only a single-phase output.